A nickel-metal hydride storage battery, nickel-cadmium storage battery, nickel-zinc storage battery, and the like, have been used as alkaline storage batteries. The nickel-metal hydride storage battery that has a high output and is environmentally safe is especially widely used.
A nickel-metal hydride storage battery uses nickel hydroxide for a positive electrode and a hydrogen absorbing alloy for a negative electrode.
The nickel-metal hydride storage battery has recently been used as an electric source for electric vehicles, hybrid electric vehicles, electric bicycles, power tools, and the like. The battery is desired to have high capacity and sufficient capacity when the battery is discharged at a high electric current.
An alkaline storage battery with improved discharge characteristics has been proposed that is provided by the addition of an oxide or ions of Al, Ga, Ge, and the like, to a negative electrode containing a hydrogen absorbing alloy or to an alkaline electrolyte to reduce excess voltage during discharge as disclosed in Japanese patent publication (Tokkou) No. 3,118,832.
However, even such an improved alkaline storage battery generates oxygen at the positive electrode when charge depth is increased, and a high capacity cannot be obtained. There is a problem that discharge characteristics also cannot be improved sufficiently and discharge capacity is reduced when the battery is discharged at a high electric current.